Motorized mobile shelving units

ABSTRACT

Storage apparatus which includes one or more mobile storage or shelving units moveable on guide tracks employs reversible electric motors in each mobile unit to move the units to open the desired access aisle. Direction-control switches located on the exposed ends of the mobile units and right and left limit switches on each of the mobile units afford selective energization of the motors to open the desired aisle.

United States Patent Staller et al.

[ 51 Feb. 8, 1972 [54] MOTORIZED MOBILE SHELVING UNITS [72] Inventors: Maurice F. Staller; Marvin A. Staller, both of Fort Atkinson, Wis.

[73] Assignee: Staller Cabinet, Inc., Fort Atkinson, Wis.

[22] Filed: May 6, 1970 [21] Appl. No.: 35,214

[52] U.S.Cl ..312/l98, l04/l47,2l4/16 B, 312/200 [51 Int. Cl. ..A47b 53/00, A47b 77/00, A47b 87/00 [58] Field ofSearch ..3l2/198, 199,200, 8.5; 214/16 B, 6 T; 220/60; 104/147, 162, 152, 276, 235; 211/143 156] References Cited UNITED STATES PATENTS 3,198,592 8/1965 Zippel ..l04/162 X 3,188,977 6/1965 Viktorssonm. ..104/235 2,605,911 8/1952 Medway.... ..2l4/16.14 C 2,602,557 7/1952 Sinclair 214/1616 B 2,654,489 10/1953 1ngold.... 312/199 2,772,639 12/1956 lngoldi... ..l04/1lt\ 2,915,195 12/1959 Crosby 311/19 Primary Examiner-Casmir A. Nunbcrg Attorney-Wheeler, House & Wheeler 7] ABSTRACT Storage apparatus which includes one or more mobile storage or shelving units moveable on guide tracks employs reversible electric motors in each mobile unit to move the units to open the desired access aisle. Direction-control switches located on the exposed ends of the mobile units and right and left limit switches on each of the mobile units afford selective energization of the motors to open the desired aisle.

16 Claims, 13 Drawing Figures MOTORIZED MOBILE SI'IELVING UNITS BACKGROUND OF INVENTION The invention relates to storage systems utilizing mobile shelving units which are guided for movement on tracks. A storage system of this type is disclosed in US. Pat. No. 3,427,085. More particularly, the invention relates to mobileshelving units which are moved by electric motors. Prior art storage apparatus utilizes a single stationary electric motor which drives an endless chain or cable. The mobile shelving units are connected and disconnected to the chain or cable by various clutching arrangements. Special floors are required to recess the drive apparatus. Apparatus of this type is shown in US. Pat. No. 2,772,639. Other prior storage apparatus utilizing a single motor and an endless chain, requires critical spacing of the stationary units and a predetermined length for the guide rails to accommodate the programmed control sequence.

SUMMARY OF INVENTION The invention provides storage apparatus which includes one or more mobile storage units with each of the mobile storage units including a carriage and load-supporting wheels guided for movement on guide rails. The mobile units are typically employed with stationary end units with the guide rails spanning the distance between the stationary units. Each of the mobile units is provided with a reversible electric motor which drives a rubber drive wheel which engages a guide rail. Storage units over feet in length may require two or more drive wheels and those less than 15 feet only one drive wheel. A line shaft driven by the motor supplies power to the drive wheels.

A control circuit is provided to selectively energize the motors to move the mobile storage units as required to open an aisle between stationary or end storage units and a mobile storage unit or between adjacent mobile storage units to afford access to the shelf faces. The control circuit can include two directional control switches on the exposed end of one of the mobile units with the switches located adjacent the shelf faces and a single direction-control switch adjacent one shelf face on all of the other mobile units.

Each mobile unit has two limit switches. The limit switches have outwardly biased control rods projecting in the direction of travel of the mobile units and parallel with the guide rails. The limit switches are closed when in their outermost position and open when in engagement with limit-switch stops on the stationary units or when the control rods of adjacent mobile units are in mutual engagement and the adjacent faces of the mobile units are abutting.

The direction-control switches and the limit switches are connected in the circuit so that the desired aisle is opened by actuation of the control switch closest to the shelf face to which access is desired. The motor of the mobile unit which has a closed limit switch will be energized first and the mobile unit will move in the necessary direction. As the first unit to move separates from an adjacent mobile unit, the limit switch on the adjacent unit will be released from its depressed position and close to energize the motor of the second mobile unit. The energized units continue to move until their limit switches open upon engaging limit switch stops or limit switch control rods of adjacent units.

The use of individual motors for each mobile unit eliminates the need for an endless chain and a specially recessed floor. The use of limit switches for controlling movement of the mobile units affords the use of varying aisle widths between the mobile units and the end units.

Torque-limiting devices in the drive trains between the motors and the line shafts minimize the forces applied to the mobile units to prevent crushing of cartons, etc., which may be inadvertently left in an aisle.

Each of the mobile units is provided with a cable-takeup assembly. The cable contains the connecting leads between the mobile units. The takeup assemblies pay out stored lengths of cable as the mobile units separate.

The invention also provides load wheel assemblies for the mobile units which employ two spaced load wheels aligned longitudinally of the guide rails which they frictionally engage. The load wheels are supported by horizontal axlesjoumaled in spaced sideplates. The sideplates are supported in closely spaced vertical flanges of carriage crossmembers by a horizon tal axle located intermediate the load wheel axles. To prevent closing of the mobile units when an object or person is in an aisle, the aisles are desirably provided with floating floor portions with limit switches under the floors. When the floors are depressed, the switches open the control circuit and prevent operation of the motors.

Further objects and advantages of the present invention will become apparent from the following disclosure.

DESCRIPTION OF DRAWINGS FIG. I is a diagrammatic side elevational view of mobile storage apparatus in accordance with the invention in a first position.

FIG. 2 is a view similar to FIG. I with the mobile storage units in a second position.

FIG. 3 is a view similar to FIG. 1 with the mobile units in a third position.

FIG. 4 is an enlarged rear elevational view of one of the mobile storage units shown in FIG. 1.

FIG. 5 is a fragmentary side elevational view of a portion of a mobile storage unit carriage and a load wheel assembly.

FIG. 6 is a sectional view taken along line 6-6 of FIG. 5.

FIG. 7 is a sectional view taken along line 77 of FIG. 5.

FIG. 8 is a sectional view taken along line 8-8 of FIG. 5.

FIG. 9 is a fragmentary sectional view taken along line 9-9 of FIG. 8.

FIG. 10 is a sectional view taken along line 10--I0 of FIG. 4.

FIG. 1 l is a plan view of a mobile unit carriage.

FIG. 12 is a schematic diagram of the electrical circuit of the invention.

FIG. 13 is an enlarged fragmentary sectional view of a floating floor in an aisle.

FIG. I4 is an enlarged perspective view of a limit switch shown in FIG. 4.

DESCRIPTION OF PREFERRED EMBODIMENT Although the disclosure hereof is detailed and exact to enable those skilled in the art to practice the invention, the physical embodiments herein disclosed merely exemplify the invention which may be embodied in other specific structures. The

scope of the invention is defined in the claims appended hereto.

FIG. I shows storage apparatus in accordance with one embodiment of the invention and which optionally includes two stationary or fixed storage units or shelving assemblies 10 and I2 which have faces 14 and I6. Located between the end storage units I0 and I2 are intermediate mobile storage units 18 and 20 having faces 21, 22, 23, 24 typically provided with shelves (not shown).

In accordance with the invention, means are provided for supporting and guiding the mobile storage units 18 and 20 for movement in a direction normal to the storage unit faces and between the spaced stationary storage units 10 and 12. In the disclosed construction, the means comprises a series of spaced parallel guide rails 26 (FIGS. 6 and II). The guide rails 26 are anchored to the floor 27 by suitable fasteners (not shown). The mobile storage units 18 and 20 are supported on carriages 30 which include a pair of spaced Z-beams or sills 32 and 34 (FIG. II) which extend at right angles to the rails 26 and which are interconnected by crossbeams 36 which are parallel to the guide rails 26. The carriages 30 are supported on rails 26 by load wheel assemblies 38 which include two load wheels 40 and 42 which are rotatably supported on horizontal axles 44 and 46. The horizontal axles are journaled in a pair of spaced sideplates 48 and 50, which are located in the gap 49 between the vertical flanges SI. 53 of carriage crossmembers 52, 54. The sideplates 48, 50 are supported by horizontal axles 56 which are located between the load wheel axles and which are received in apertures 58 in the vertical flanges 51, 53. The single pivotal axis for the plates 48 and 50 provided by the axles 56 insures contact of both load wheels 40 and 42 with the guide rails 26 to evenly distribute the load of the mobile units.

The load wheel assemblies 38 also include two guide wheels 60 and 62 (FIG. 8) which are rotatably supported on threaded, vertical shafts received in offset or eccentric apertures 64 in mounting nuts 66, supported on the crossmembers 52 and 54. The eccentric mounting of the guide wheels affords lateral adjustment of the wheels 60, 62 with respect to the guide rails 26. I

In accordance with the invention, each mobile storage unit 18 and 20 is provided with a reversible motor 80 for moving the mobile units along the guide rails 26. The motors 80, 82 have an integral gear-reduction unit 83 and a torque-limiting device 84 with a sprocket which drives a chain 88. The chain 88 drives a sprocket 90 which is fixedly secured to a line shaft 92 which is supported on the carriage 30 by pillow blocks 94. One or more sprockets 96 connected to the line shaft 92 drive chains 98 connected to sprockets 100. The sprockets 100 are integrally connected to rubber drive wheels 102 which are rotatably supported on axles 103, which are joumaled in the vertical flanges 52, 54.

If the mobile storage units 18, 20 are less than feet long, a single drive wheel 102 can be employed. Where the mobile units are more than l5 feet in length, the line shaft 92 can drive one or more additional drive wheels 102, each associated with a different guide track 26.

A control circuit 120 is provided for selectively energizing the motors 80, 82 of the mobile units 18 and to move each of the units in the required direction to open an aisle to afford the desired access to the shelving faces of the storage units. The control circuit 120 (FIG. 12) includes left and right direction-control relays 122 and 124 for unit 18 and left and right direction-control relays 126 and 128 for mobile unit 20. The relay coil 122 controls normally open relay contacts 130 and relay 124 controls normally closed contacts 142 and normally open contacts 132. The relay coil 126 controls normally open contacts 136 and normally closed contacts 138. The relay coil 128 controls normally closed relay contacts 139 and normally open relay contacts 141.

The mobile units 18, 20 each have right and left limit switch assemblies, respectively 142, 144, 146, 148 (FIG. 1 and 12). The limit switch assemblies include mounting brackets 149 (FIG. 4, 14) which can be provided with slots 151 for adjustably mounting the brackets 149 on the storage units. The limit switch assemblies also include spring-loaded control rods 150, which are received in bushings 153 located in coaxial apertures 152 in the brackets 149. The control rods 150 can be formed from elongated bolts having a head 154 and a threaded portion 156, which threadably receives a knob 158. The control rods are biased outwardly by a spring 157. The actuating levers 160 of the limit switches are received in grooves or neck portions 162 on the control rods 150 when the control rods are located in their outermost positions, thus closing the switch. Inward axial movement of the control rods against the bias of springs 157 depresses the actuating lever 160 to open the switches. The control rods 150 project several inches beyond the faces of the mobile units as shown in FIG. 4 to cause opening of the limit switches and deenergization of the motors 80, 82 prior to physical contact of the adjacent faces of the units as they move into position as hereinafter described in detail.

The control circuit for mobile unit 18 includes manually actuated direction-control means comprising switches 164 and 166 (FIG. 1 and 12) which have their actuators or buttons respectively located adjacent the left and right edges or faces of unit 18. The unit 20 and any additional mobile units which may be employed has a single manually actuated control means comprising switch 168 located adjacent the right face lb.

The switches 164, 166, and 168 are located and connected in the circuit so that actuation of the switch closest to the desired access aisle will cause movement of the mobile units to open that aisle.

The electric motors 80, 82 are each provided with reversible motor starters and secondary relay assemblies respectively designated 170 and 172.

The control circuit also includes a transformer 176 which provides a 24-volt power supply for the control circuit 120 for energizing the relays and the motor starters.

The mobile units 18 and 20 are each provided with a cable storage and takeup assembly 178 (FIG. 4) for the connecting leads between the two mobile units. The connecting leads are contained in a single connecting cable 180. The takeup assemblies 178 release cable as required to permit unimpeded movement of the mobile units. Each cable-storage assembly includes a vertical guide track 182 (FIG. 10) on a vertical partition 183 on the mobile units. The guide track 182 receives a vertically shiftable pulley-mounting block 184 which rotatably supports a pulley 186. The block 184 is drawn downwardly by a spring-loaded reel 188, which contains a length of wire 190 which has an end 192 connected to the mounting block 184. The cable 180 is reeved about pulley 186 in response to tension on cable 180 caused by movement of a mobile unit will provide the required payout of cable.

In use of the storage apparatus of the invention if it is desired to move the mobile units from the position shown in FIG. 1 to the position shown in FIG. 2 to open aisle 190, the direction-control switch closest to aisle 190, namely switch 168, is actuated which thus energizes the relay coil 128, which closes contacts-141 and opens contacts 139. The closing of switch 168 also energizes relay coil 24 which causes normally open contacts 134 to close and contacts 132 to open. The left limit switch 142 on mobile unit 18 is closed when unit 18 is in the FIG. 1 position, since the control rod of limit switch 142 is in its axially outermost position. With limit switch 142 closed, the lead 200 from the 24-v. transformer 172 will be connected to the lead 202 of the motor starter to energize the motor 80 and move the unit 18 to the left toward the stationary-storage unit 14. The motor of unit 18 will be energized until the control rod of limit switch 142 engages stop 204 on stationary unit 10. Movement of the control rod, approximately A of an inch, will open the limit switch 142 and deenergize the motor 80 in unit 18. The unit 18 will coast until it abuts the face 14 of the stationary unit 10, as shown in FIG. 2.

When the unit 18 is in the position shown in FIG. 1, the control rod of the limit switch 146 on mobile unit is depressed due to engagement with the control rod of the adjacent limit switch 144, and is therefore, in an open position. As the unit 18 moves a few inches away from unit 20, upon actuation of switch 168, the limit switch 146 closes and the motor 82 for mobile unit 20 is energized by completion of the circuit from lead 200 to lead 204, thus causing unit 20 to travel in sequence in spaced relation from the mobile unit 18. The unit 20 will move to the left until the control rod of the limit switch 146 engages the adjacent control rod for limit switch 144 to deenergize the motor 82 and permit unit 20 to coast against unit 18 forming the aisle 190.

If it is desired to move the units 18 and 20 from the position shown in FIG: 1 to the position of FIG. 3 to open aisle 191 for access to face 22 of unit 18, the control switch closest to the face 22 or switch 166 is actuated. The switch 166 will energize relay coil 124 to close contacts 132 and energize the motor starter and motor 80 of unit 18. Since only limit switch 142 is closed when the mobile units are in this position, the unit 18 will move to the left until the limit switch 142 engages the stop 204.

The storage apparatus of the invention also includes various safety apparatus including drive sockets 206 at the ends of the line shafts 92 (FIG. 11). In the event of a power failure, the mobile units can be moved by inserting a suitable wrench in the socket.

The aisle spaces can optionally be provided with floating lloor portions or segments 20H, 2I0. 212 (FIG. I, 13). The

floor segments are supported for vertical movement on limit switches or other pressure-sensitive switches 214, which are normally open and closed when a carton or person, etc., is on the floor segment and the floor segment is depressed. When any of the switches 214 closes, the coil 218 of an emergency stop relay is energized and the contacts 220 are opened, interrupting the 24-v. control circuit to prevent movement of the mobile units.

The circuit can also include a row of terminals 224 for connection to additional mobile storage units. Although the disclosed storage apparatus employs two mobile storage units, additional mobile units can be employed between the two stationary units. Alternate arrangements can include three or more stationary units with groups of mobile units located between the stationary units.

The storage apparatus of the invention is easily installed by fastening the guide rails to an existing floor. Special recessed floors are not required as with some prior art storage ap paratus. Furthermore, the length of the guide rails is not critical and the width of the aisles can be varied. The use of line shafts for powering the drive wheels permits the mobile units to be constructed in different lengths.

What is claimed is:

1. Storage apparatus comprising a plurality of mobile storage units, each unit having at least one storage face, guide means cooperating with said mobile units to guide movement of said storage units in a direction normal to said faces of said storage units, a separate motor individual to each of said mobile units for individually driving said unit along said guide means, and control-circuit means for selectively energizing and deenergizing a motor on one unit in response to movement of a different unit, to move said storage units as required to open an aisle between selected storage units.

2. Storage apparatus in accordance with claim 1, wherein said control-circuit means includes for each unit a manually actuated control-switch actuator against a face thereof, and means responsive to actuation of the control-switch actuator for moving the storage units as required to afford access to said face.

3. Apparatus in accordance with claim 1 wherein, said control circuit includes first and second limit switches on each of said mobile units said limit switches having control members and being open when said control members are in engagement with an adjacent storage unit and closed when in nonengagement with a storage unit, and said limit switches being connected in said control circuit to afford sequential energization of said motors in said mobile units as said limit switches close upon separation of said mobile units and sequential deenergization of said motors as said control members successively engage adjacent storage units.

4. Apparatus in accordance with claim 1 wherein, said drive means includes a line shaft rotatably supported on each of said mobile units, means drivingly connecting said line shaft to said motor, a drive wheel supported on said mobile unit and engageable with said guide means, and means drivingly connecting said line shaft to said drive wheel.

5. Apparatus in accordance with claim 4 including a second drive wheel rotatably supported on said mobile unit and engageable with said guide means and means drivingly connecting said line shaft to said second drive wheel.

6. Apparatus in accordance with claim 4 wherein, said means drivingly connecting said line shaft to said motor means includes a torque-limiting device on said motor.

7. Storage apparatus comprising a plurality of mobile storage units, each unit having at least one storage face, guide means cooperating with said mobile units to guide movement of said storage units in a direction normal to said faces of said storage units, a separate motor individual to each of said mo bile units for individually driving said unit along said guide means, and control-circuit means for selectively energizing each said motor in a sequence in which said storage units are moved as required to open an aisle between selected storage units and wherein each of said mobile units has a vertical partition, a cable-takeup assembly including a vertical track on said partition, a pulley-mounting block movable in said track. a pulley rotatably supported on said block, biasing means connected to said mounting block for drawing said mounting block downwardly in said track, and a second pulley rotatably supported on said storage-unit partition and a cable reeved around said first and second pulleys.

8. Storage apparatus comprising a plurality of mobilestorage units, each unit having at least one storage face, guide means cooperating with said mobile units to guide movement of said storage units in a direction normal to said faces of said storage units, a separate motor individual to each of said mobile units for individually driving said unit along said guide means, and control-circuit means for selectively energizing each said motor in a sequence in which said storage units are moved as required to open an aisle between selected storage units and including floorboards for aisles between said storage units, said floorboards being supported for vertical movement and electrical switches under said floorboards, said switches being actuated by pressure on said floorboards.

9. Storage apparatus comprising a plurality of mobile storage units, each unit having at least one storage face, guide means cooperating with said mobile units to guide movement of said storage units in a direction normal to said faces of said storage units, a separate motor individual to each of said mobile units for individually driving said unit along said guide means, and controlcircuit means for selectively energizing each said motor in a sequence in which said storage units are moved as required to open an aisle between selected storage units and wherein, said guide means comprises a plurality of spaced guide rails and wherein each of said mobile storage units has a carriage having a pair of spaced sills at right angles with said guide rails and shelf assemblies supported on said sills, said sills being interconnected by pairs of crossmembers having spaced vertical flanges, load wheel assemblies located between said vertical flanges, each of said load wheel assemblies including a pair of spaced sideplates, first and second load wheels between said sideplates and engaging said guide rails, said load wheels having horizontal axles supported in said sideplates and an intermediate axle connecting said sideplates and located between said load wheels, said intermediate axle being journaled in said vertical flanges for supporting said load wheel assemblies and said carriages.

10. Storage apparatus comprising a pair of spaced stationary storage units, first and second mobile storage units, each of said units having shelving faces and a carriage, guide rails cooperating with said carriages to guide movement of said storage units in a direction normal to said faces of said storage units and between said stationary storage units, reversible motors for each of said mobile storage units, drive means connected to said motors for moving said mobile storage units and a control circuit including directional control switches on said mobile units, first and second limit switches on each of said a mobile units and limit switch stops on each of said stationary storage units, said limit switches being open when faces of said storage units are abutting and closed when said faces are spaced apart, said directional control switches and limit switches being electrically connected to said motors so that actuation of one of said directional control switches will initially cause energization of said motor in said mobile storage unit which has a closed limit switch and sequentially energize the motor of said other mobile storage unit as said limit switch of said other unit closes as said first unit to be energized moves away from said other unit, and said motor for said first mobile storage unit becoming deenergized as one of said limit switches on said first said mobile storage unit engages a stop on one of said stationary storage units and said motor on said other mobile storage unit being sequentially deenergized as said other mobile unit moves to the desired position and one of said limit switches on said other unit engages a limit switch stop.

11. Apparatus in accordance with claim 10 wherein, said control circuit includes right and left directional control relays supported on each of said mobile units and a low voltage power source on one of said mobile units for energizing said relays and an electrical cable interconnecting said relays on each of said mobile units.

12. Storage apparatus comprising a plurality of mobile storage units, each unit having at least one storage face, guide means cooperating with said mobile units to guide movements of said storage units in a direction normal to said faces of said storage units, a separate motor individual to each of said mobile units for individually driving said unit along said guide means, and control circuit means for selectively energizing each said motor in a sequence in which said storage units are moved as required to open an aisle between selected storage units and wherein, said control circuit means include limit switches for said motors, said limit switches being located in the paths of movement of said units for sequential actuation of said motors as said units move sequentially on said paths.

13. Storage apparatus comprising a plurality of mobile storage units, guide means for guiding movement of said storage units and a separate motor supported in each of said mobile units for moving said mobile units along said guide means to open an access aisle between selected storage units, each of said mobile units having a manually actuated control means and right and left limit switches, said switches being electrically connected to the unit motor, means for actuating said right limit switch when an adjacent unit is at the right of the unit with no aisle space therebetween, means for actuating said left limit switch when an adjacent unit is at the left of the unit with no aisle space therebetween, and control circuit means including said right and left limit switches to energize the unit motor to move the unit in the direction of an open aisle space when a manually actuated control means is actuated.

14. Apparatus in accordance with claim 13 including a drive wheel supported on each of said mobile units and drivingly engaged with said guide means and means connecting said motors to said drive wheels. 

1. Storage apparatus comprising a plurality of mobile storage units, each unit having at least one storage face, guide means cooperating with said mobile units to guide movement of said storage units in a direction normal to said faces of said storage units, a separate motor individual to each of said mobile units for individually driving said unit along said guide means, and control-circuit means for selectively energizing and deenergizing a motor on one unit in response to movement of a different unit, to move said storage units as required to open an aisle between selected storage units.
 2. Storage apparatus in accordance with claim 1, wherein said control-circuit means includes for each unit a manually actuated control-switch actuator against a face thereof, and means responsive to actuation of the control-switch actuator for moving the storage units as required to afford access to said face.
 3. Apparatus in accordance with claim 1 wherein, said control circuit includes first and second limit switches on each of said mobile units said limit switcHes having control members and being open when said control members are in engagement with an adjacent storage unit and closed when in nonengagement with a storage unit, and said limit switches being connected in said control circuit to afford sequential energization of said motors in said mobile units as said limit switches close upon separation of said mobile units and sequential deenergization of said motors as said control members successively engage adjacent storage units.
 4. Apparatus in accordance with claim 1 wherein, said drive means includes a line shaft rotatably supported on each of said mobile units, means drivingly connecting said line shaft to said motor, a drive wheel supported on said mobile unit and engageable with said guide means, and means drivingly connecting said line shaft to said drive wheel.
 5. Apparatus in accordance with claim 4 including a second drive wheel rotatably supported on said mobile unit and engageable with said guide means and means drivingly connecting said line shaft to said second drive wheel.
 6. Apparatus in accordance with claim 4 wherein, said means drivingly connecting said line shaft to said motor means includes a torque-limiting device on said motor.
 7. Storage apparatus comprising a plurality of mobile storage units, each unit having at least one storage face, guide means cooperating with said mobile units to guide movement of said storage units in a direction normal to said faces of said storage units, a separate motor individual to each of said mobile units for individually driving said unit along said guide means, and control-circuit means for selectively energizing each said motor in a sequence in which said storage units are moved as required to open an aisle between selected storage units and wherein each of said mobile units has a vertical partition, a cable-takeup assembly including a vertical track on said partition, a pulley-mounting block movable in said track, a pulley rotatably supported on said block, biasing means connected to said mounting block for drawing said mounting block downwardly in said track, and a second pulley rotatably supported on said storage-unit partition and a cable reeved around said first and second pulleys.
 8. Storage apparatus comprising a plurality of mobile-storage units, each unit having at least one storage face, guide means cooperating with said mobile units to guide movement of said storage units in a direction normal to said faces of said storage units, a separate motor individual to each of said mobile units for individually driving said unit along said guide means, and control-circuit means for selectively energizing each said motor in a sequence in which said storage units are moved as required to open an aisle between selected storage units and including floorboards for aisles between said storage units, said floorboards being supported for vertical movement and electrical switches under said floorboards, said switches being actuated by pressure on said floorboards.
 9. Storage apparatus comprising a plurality of mobile storage units, each unit having at least one storage face, guide means cooperating with said mobile units to guide movement of said storage units in a direction normal to said faces of said storage units, a separate motor individual to each of said mobile units for individually driving said unit along said guide means, and control-circuit means for selectively energizing each said motor in a sequence in which said storage units are moved as required to open an aisle between selected storage units and wherein, said guide means comprises a plurality of spaced guide rails and wherein each of said mobile storage units has a carriage having a pair of spaced sills at right angles with said guide rails and shelf assemblies supported on said sills, said sills being interconnected by pairs of crossmembers having spaced vertical flanges, load wheel assemblies located between said vertical flanges, each of said load wheel assemblies including a pair of spaced sideplates, first and second load wheels between said sideplates and engaging said guide rails, said load wheels having horizontal axles supported in said sideplates and an intermediate axle connecting said sideplates and located between said load wheels, said intermediate axle being journaled in said vertical flanges for supporting said load wheel assemblies and said carriages.
 10. Storage apparatus comprising a pair of spaced stationary storage units, first and second mobile storage units, each of said units having shelving faces and a carriage, guide rails cooperating with said carriages to guide movement of said storage units in a direction normal to said faces of said storage units and between said stationary storage units, reversible motors for each of said mobile storage units, drive means connected to said motors for moving said mobile storage units and a control circuit including directional control switches on said mobile units, first and second limit switches on each of said mobile units and limit switch stops on each of said stationary storage units, said limit switches being open when faces of said storage units are abutting and closed when said faces are spaced apart, said directional control switches and limit switches being electrically connected to said motors so that actuation of one of said directional control switches will initially cause energization of said motor in said mobile storage unit which has a closed limit switch and sequentially energize the motor of said other mobile storage unit as said limit switch of said other unit closes as said first unit to be energized moves away from said other unit, and said motor for said first mobile storage unit becoming deenergized as one of said limit switches on said first said mobile storage unit engages a stop on one of said stationary storage units and said motor on said other mobile storage unit being sequentially deenergized as said other mobile unit moves to the desired position and one of said limit switches on said other unit engages a limit switch stop.
 11. Apparatus in accordance with claim 10 wherein, said control circuit includes right and left directional control relays supported on each of said mobile units and a low voltage power source on one of said mobile units for energizing said relays and an electrical cable interconnecting said relays on each of said mobile units.
 12. Storage apparatus comprising a plurality of mobile storage units, each unit having at least one storage face, guide means cooperating with said mobile units to guide movements of said storage units in a direction normal to said faces of said storage units, a separate motor individual to each of said mobile units for individually driving said unit along said guide means, and control circuit means for selectively energizing each said motor in a sequence in which said storage units are moved as required to open an aisle between selected storage units and wherein, said control circuit means include limit switches for said motors, said limit switches being located in the paths of movement of said units for sequential actuation of said motors as said units move sequentially on said paths.
 13. Storage apparatus comprising a plurality of mobile storage units, guide means for guiding movement of said storage units and a separate motor supported in each of said mobile units for moving said mobile units along said guide means to open an access aisle between selected storage units, each of said mobile units having a manually actuated control means and right and left limit switches, said switches being electrically connected to the unit motor, means for actuating said right limit switch when an adjacent unit is at the right of the unit with no aisle space therebetween, means for actuating said left limit switch when an adjacent unit is at the left of the unit with no aisle space therebetween, and control circuit means including said right and left limit switches to energize the unit motor to move the unit in the direction of an open aisle space when a manually actuated control means is actuated.
 14. Apparatus in accordance with claim 13 including a drive wheel supported on each of said mobile units and drivingly engaged with said guide means and means connecting said motors to said drive wheels.
 15. The apparatus of claim 13 in which the means for actuating one of said left and right limit switches comprises a shiftable rod physically actuated by an adjacent unit.
 16. The apparatus of claim 14 in which the means for actuating said left and right limit switches comprises aligned shiftable rods mounted on adjacent units and by which motion is transmitted from one rod to another. 